A Missouri man set to be executed on Tuesday in the killing of his former lover maintains his innocence, telling a local newspaper: "You cannot show remorse for something you did not do."

David Hosier, 69, is set to be put to death by lethal injection for the 2009 murder of Angela Gilpin, a mother of two who was killed alongside her husband, Rodney Gilpin.

Hosier has maintained his innocence since his conviction, pointing to a lack of physical evidence tying him to the scene and ineffectual lawyers during trial. With the last of his appeals exhausted Monday, Hosier is set to become the second inmate executed in the state this year and the seventh in the United States.

"I would not say that he is at peace," Hosier's attorney, Jeremy Weis, told USA TODAY in an interview last week.

USA TODAY is looking back at the murders, who David Hosier was before the crime, what shaped his life, and what he argued about the upcoming execution.

What led up to the killing of Angela and Rodney Gilpin?

Hosier and the Gilpins lived in nearby apartments in Jefferson City, Missouri, where the three first met at a local bar.

Sometime in 2008 or 2009 while the Gilpins were separated, Hosier and Angela Gilpin began having a love affair. It's unclear how long it lasted but Gilpin decided she was going to stay with her husband and ended things with Hosier, who was overheard saying that if Gilpin “would not come back with him” then he “would put a stop to it somehow," according to court records.

Two weeks before she was killed, Gilpin applied for a restraining order against Hosier and was looking to move apartments, writing to her landlord that she could no longer live next to Hosier, saying: "He scares me. I don't know he will do next."

The day before the killings, Hosier left a voicemail for a friend saying that he was going to "finish it" and called another one to say that he was going to "eliminate his problems," court records show.

Angela and Rodney Gilpin found dead

During the early morning of Sept. 28, 2009, a neighbor found the Gilpins dead, their bodies in the threshold of their apartment. They had both been shot multiple times.

It didn't take long for police to find Angela Gilpin's application for a protective order from Hosier, telling a court that he was stalking and harassing her every day. Later that day following a pursuit, police arrested Hosier, who told officers: "Shoot me and get it over with," according to court documents.

When officers searched the car, they found 15 firearms, including a STEN submachine gun, ammunition and a handwritten note that read: "If you are going with someone, do not lie to them, do not play games with them, do not (expletive) them over by telling other people things that are not true.

"Be honest with them and tell them if there is something wrong," the note continued. "If you do not, this could happen to you."

Who is David Hosier?

The youngest of three children, Hosier grew up in Indiana in the 1950s and 1960s.

His early life was shaped by one traumatic event that his family says turned him into the man he became: When he was just 16 years old, his police officer father was shot and killed while trying to apprehend a murder suspect.

“I lost my best friend," Hosier told the Kansas City Star in a recent interview.

The event marked the beginning of a downward spiral for Hosier, his family said in a clemency video submitted to Parson's office in hopes that the governor will spare Hosier from the death penalty.

"He's been angry with all the women in his life, including me and my mother and it was not like that for him before my dad died," Hosier's sister, Kay Schardien, says in the clemency video. "My dad's death was just like a crater and David fell into that crater."

At the age of 19, Hosier joined the U.S. Navy, marrying while he was enlisted but divorcing before he was discharged.

He later remarried in 1980 and had a son and a daughter. That marriage ended in 1987, a year after he had been involuntarily committed to the psychiatric ward of a state hospital, according to his clemency petition.

In 1993, Hosier pleaded guilty to battering his then-girlfriend and was sentenced to eight years in prison. He was released on parole in 1997.

In a recent phone interview with The Associated Press, Hosier said that he felt his clemency petition focused too much on the death of his father, rather than on the evidence in the case.

“I told them I didn’t want the ‘boo-hoo, woe is me,’" the AP reported. "All that stuff happened 53 years ago, OK? It has nothing to do with why I’m sitting here right now.”

David Hosier's appeals argue lack of evidence

In appeals, Hosier's lawyers argue that there was a lack of physical evidence tying Hosier to the scene of the murder, including the state's ballistics expert's inability to identify that the bullets found at the crime scene.

They also argue that he had ineffective attorneys during trial, saying that among other failings, they should have struck two unqualified jurors and failed to present a witness who could have told jurors about a stroke Hosier had in 2007 that caused brain damage.

Weis, Hosier's current attorney, told USA TODAY that jurors did see medical records of Hosier's stroke and depressive episodes but a medical professional could have better explained their significance.

"Essentially, they took all these medical records and said, 'Well, you figure it out,'" Weis said. "When we discussed with the jurors that this information existed and would (it) have made a difference and would you wanted to know this when you were making your decision, they almost universally said yes."

Hosier also argued that the judge who presided over his trial and sentencing had a conflict of interest, having prosecuted him in 1998 for failing to pay child support.

Weis also pointed to a plea offer of life without the possibility of parole that Hosier turned down as evidence that the state was willing to accept less than a death sentence in the case.

Republican Missouri Gov. Michael Parson denied Hosier's request for clemency on Monday, one of his final chances to avoid the death penalty.

"Ms. Angela Gilpin had her life stolen by David Hosier because he could not accept it when she ended their romantic involvement. He displays no remorse for his senseless violence," Parson said in a statement announcing the decision. "I cannot imagine the pain experienced by Angela’s and Rodney’s loved ones but hope that carrying out Hosier’s sentence according to the Court’s order brings closure."

Hosier's state of mind ahead of execution day

Hosier was placed in solitary confinement on Feb. 14 after the Missouri Supreme Court set the June 11 execution date. He was hospitalized for heart failure in May.

Weis described Hosier's condition as having "deteriorated" since being moved from the general population at Potosi Correctional Center, about 70 miles south of St. Louis.

"I would not say that he is at peace," Weis said. "The things that that people rely on in the institution, the friendships, the camaraderie of people that have been there a long time and are in a similar situation are all removed from them all of a sudden. You're kind of on an island."

Weis said that Hosier has developed a close relationship with his spiritual advisor, the Rev. Jeff Hood, as the scheduled execution day draws closer.

"David gets a sense that 'This person is pulling for me, is willing to meet with me and is just open to being open to him as a human being,'" Weis said.

Hosier told the Kansas City Star that he and Hood "talk a lot about the Bible and different things."

“We talk, just trying to get prepared for the state wanting to murder you," he said, adding that though he may have supported the death penalty following his father’s death, he no longer does so after having gone through the system.

“I can’t see by any justification, the death penalty as being anything but cruel and inhumane,” Hosier told the newspaper. “The state says it’s illegal for us to kill somebody, but they can sanction a murder and it’s A-OK, no big deal.”

Though he said he was sorry that the Gilpins were killed (“nobody deserves anything like that”), he maintains his innocence and said he's just disappointed in the attorneys who previously represented him.

“I’m disappointed that they missed it, but I can’t fault them because we’re all human,” he told the Star. “Humans make mistakes. So consequently, I’m sitting here with an execution date, waiting to die.”